Detailed Description

The QWhatsThis class provides a simple description of any widget, i.e. answering the question "What's This?".

"What's This?" help is part of an application's online help system, and provides users with information about the functionality and usage of a particular widget. "What's This?" help texts are typically longer and more detailed than tooltips, but generally provide less information than that supplied by separate help windows.

QWhatsThis provides a single window with an explanatory text that pops up when the user asks "What's This?". The default way for users to ask the question is to move the focus to the relevant widget and press Shift+F1. The help text appears immediately; it goes away as soon as the user does something else. (Note that if there is a shortcut for Shift+F1, this mechanism will not work.) Some dialogs provide a "?" button that users can click to enter "What's This?" mode; they then click the relevant widget to pop up the "What's This?" window. It is also possible to provide a a menu option or toolbar button to switch into "What's This?" mode.

The text can be either rich text or plain text. If you specify a rich text formatted string, it will be rendered using the default stylesheet, making it possible to embed images in the displayed text. To be as fast as possible, the default stylesheet uses a simple method to determine whether the text can be rendered as plain text. See Qt::mightBeRichText() for details.

newAct =newQAction(tr("&New"),this);
newAct->setShortcut(tr("Ctrl+N"));
newAct->setStatusTip(tr("Create a new file"));
newAct->setWhatsThis(tr("Click this option to create a new file."));

An alternative way to enter "What's This?" mode is to call createAction(), and add the returned QAction to either a menu or a tool bar. By invoking this context help action (in the picture below, the button with the arrow and question mark icon) the user switches into "What's This?" mode. If they now click on a widget the appropriate help text is shown. The mode is left when help is given or when the user presses Esc.

Member Function Documentation

Returns a ready-made QAction, used to invoke "What's This?" context help, with the given parent.

The returned QAction provides a convenient way to let users enter "What's This?" mode.

[static] void QWhatsThis::enterWhatsThisMode()

This function switches the user interface into "What's This?" mode. The user interface can be switched back into normal mode by the user (e.g. by them clicking or pressing Esc), or programmatically by calling leaveWhatsThisMode().

When entering "What's This?" mode, a QEvent of type Qt::EnterWhatsThisMode is sent to all toplevel widgets.